It’s interesting that the slowdown in sprawl, like the slowdown in mall construction, presaged “peak car.” The directionality might be backwards: the 1980s cessation of massive freeway construction may have pushed many metro areas into some version of Marchetti’s Wall, whose daily-travel-time maximum creates a geometric limit for autocentric growth at the edge. Edge Cities, by relocating commercial uses into the inner suburbs, could only extend the outward trend so far; with a few notable examples, attempts at building Edge Cities in outer-ring suburbs has largely failed, since there’s no meaningful centrality amidst the undifferentiated masses of one-acre lots. Second-generation Edge Cities rarely thrived, because without new beltways there just wasn’t the population base to feed them.

To this day,* 80% of the office market in metro DC is within three miles of the Beltway. Joel Garreau wrote that in the late 1980s, Til Hazel “had major projects at half the exits on Interstate 66 from the Beltway to… Manassas,” but ultimately, that future didn’t pan out (with Reston-Herndon as the notable exception that proves the rule). Even in metro Boston, which uniquely among its East Coast brethren actually built an outer beltway, 73% of the office market is within the urban core or inner ring, and the urban core commands per-foot prices more than twice as high.

If you consider that the area of a circle grows with the square of its radius, a slowdown in the areas developed for sprawl would imply a much steeper decrease in the radius of metro expansion. This could imply another overlooked factor in the slowdown in VMT growth: since metro areas are no longer getting geometrically wider, thus distances between metro-area destinations are no longer growing as fast. As growth recentralizes, VMT can be expected to decline further. (A majority of the VMT benefits from central locations come from the fact that car trips are shorter; a minority of the befits come from a switch to other modes.)

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7 thoughts on “Sprawl’s inflection point was 20 years ago”

I found myself out in Tysons this past weekend, checking out the ongoing development at Tysons Corner Center. Upon returning, I found this online presentation from Macerich pitching the retail spaces that will open up in the new office and residential towers connected to the Mall and to Metro:

Their definition of the Mall’s primary trade area is illustrative of the geometric limits you mention. The primary trade area stretches to the edges of DC and out to Dulles. A location further from the Beltway risks completely abandoning the core of the city and region.

I remember saying that Chicagoans “always face the Loop,” i.e., your back’s always turned to everything further from downtown than you are. When I lived at 1600 N, I’d be much more likely to visit the grocery at 1200 N than the one at 1800 N — it’s further away, but it’s along my usual route to/fro.

A combination of lower densities and fewer high-capacity transportation links (freeways, rail lines) means that a peripheral shopping center/office park has a much smaller trade area than one more centrally located. That might have been OK back when everyone shopped at Sears and worked in widget factories, but not now that production & consumption have been hyper-specialized. More on this, and how it shapes metro growth dynamics vis-a-vis downtowns, later…

Problem I have with this analysis is the notion that sprawl growth occurs uniformly in all directions away from the city core. That is, area land use goes as radius squared. Looking at any map, this is demonstrably not true. To the contrary, sprawl growth first occurs down the main arteries, and then perpendicular to these roads. The growth patterns dendritic (see http://en.wikipedia.org/wiki/Dendrimer), like what you see in a snowflake.

This means that the development patterns do to approximate a circle; it is fractal.